This invention relates to vehicle jacks and, more particularly, to an improved handle for actuating such jacks.
Motor vehicles have traditionally been equipped with a spare wheel to use in the event that one of the tires became flat or disinflated. Along with a spare wheel, some means for raising the vehicle in order to change the wheel must be provided. This means of lifting the vehicle has usually been some form of vehicle jack.
Some vehicle jacks have heretofore been designed to be positioned underneath the vehicle, usually just to the inside of the tire to be changed and the designated lifting point is generally the axle or other nearby wheel support structure. These jacks may be either of a scissors-type or a telescoping-type and normally utilize a screw drive. In both cases, a rotary force is applied to an operator or coupling on the end of a screw drive to either raise or lower the vehicle depending upon whether the rotary motion is clockwise or counterclockwise.
To impart that rotary motion to the jack, a handle is attached to the jack spindle both, to transmit the rotary motion to the jack and, to help position the jack at the proper lifting location underneath the vehicle. The jack handle must be long enough to reach from the perimeter of the vehicle to the jack which is positioned underneath the vehicle while still allowing enough room for the operator to apply the rotary motion to the end of the handle remote from the jack.
Some of the current jack handles on the market have a solid metal end with a generally L-shaped tip or hook on one end of the jack handle. This hook is engaged with an operator on the base of the jack which allows the jack handle to be used to push and pull the jack to position it underneath the vehicle. Furthermore, the hook drivingly engages the jack operating coupling and transmits the necessary rotary motion and torque from the jack handle to the jack screw in order to lift the vehicle.
Referring to FIG. 1, to manufacture the hook and jack handle assembly, a hook 14 is formed in a first end 13 of a solid metal end piece 12 which has an opposite end 18 with a noncircular cross-section. The opposite end 18 of the end piece 12 is inserted into a tubular section 20 of the jack handle 22 and then held in place while a stake or crimp (not shown) is applied to the outer surface of the tubular section 20. In theory, the crimp should simultaneously form mating depressions in both the tubing wall 16 and opposite end 18 of the end piece 12, which should secure the end piece 12 to the end of the jack handle 22 and prevent the end piece 12 from separating from the jack handle 22 during normal use.
In practice, however, often, this is not what happens. As the crimp punch displaces the material in the tubing wall 16, the tubing wall material is merely compressed and thinned out to form a notch 26 between the crimp punch and the end piece 12, as shown in FIG. 1. The tubing wall does not displace the adjoining material in the end piece 12 as one would expect. If the crimping force is increased with the intent of causing the punch to penetrate into the end piece material, the tubing wall 16 is often punched through as shown at notch 28 in FIG. 2. Alternatively, only an extremely thin section of tube wall 16 is left in the depression formed in the end piece 12, which will not adequately retain the end piece 12 in the jack handle 22 when forces such as an axial load are applied to the hook and jack handle assembly.
In order to meet the torque requirements placed on the hook and jack handle assembly, the tensile strength of the end piece 12 is greater than the tensile strength of the tubular section 20 of the jack handle 22. This would account for the softer tubing wall 16 not being able to displace the harder end piece material. Also the thin tubing wall 16 presents a much less substantial structure than the solid end piece 12. Thus, the tubing wall 16 is simply displaced by the punch instead of being able to work the material of the end piece 12.
As a result of the tubing wall 16 not displacing the material in the end piece 12, the minimal contact between the end piece 12 and tubing wall 16 at the crimp area creates a frictional force that temporarily holds the end piece 12 in place within the jack handle 22. Once the jack handle is used, however, the forces applied to the hook 14 and jack handle 22 can cause the tubular section 20 to relax slightly, that is, to deflect or move, and the contact between the tubular section 20 and end piece 12 is lost. The end piece 12 with hook 14 can then be easily dislodged from the jack handle 22 when longitudinal forces apply an axial load, such as when the hook and jack handle assembly is used to pull the jack (not shown) from underneath the vehicle.
There is thus a need to provide a hook and jack handle assembly in which the hook will not unexpectedly separate from the jack handle during normal use of the vehicle jack.